211 lines
6.9 KiB
C
211 lines
6.9 KiB
C
/*
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* Resizable, Scalable, Concurrent Hash Table
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*
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* Copyright (c) 2014 Thomas Graf <tgraf@suug.ch>
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* Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>
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*
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* Based on the following paper by Josh Triplett, Paul E. McKenney
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* and Jonathan Walpole:
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* https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf
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*
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* Code partially derived from nft_hash
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef _LINUX_RHASHTABLE_H
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#define _LINUX_RHASHTABLE_H
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#include <linux/rculist.h>
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struct rhash_head {
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struct rhash_head __rcu *next;
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};
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#define INIT_HASH_HEAD(ptr) ((ptr)->next = NULL)
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struct bucket_table {
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size_t size;
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struct rhash_head __rcu *buckets[];
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};
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typedef u32 (*rht_hashfn_t)(const void *data, u32 len, u32 seed);
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typedef u32 (*rht_obj_hashfn_t)(const void *data, u32 seed);
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struct rhashtable;
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/**
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* struct rhashtable_params - Hash table construction parameters
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* @nelem_hint: Hint on number of elements, should be 75% of desired size
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* @key_len: Length of key
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* @key_offset: Offset of key in struct to be hashed
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* @head_offset: Offset of rhash_head in struct to be hashed
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* @hash_rnd: Seed to use while hashing
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* @max_shift: Maximum number of shifts while expanding
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* @min_shift: Minimum number of shifts while shrinking
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* @hashfn: Function to hash key
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* @obj_hashfn: Function to hash object
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* @grow_decision: If defined, may return true if table should expand
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* @shrink_decision: If defined, may return true if table should shrink
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* @mutex_is_held: Must return true if protecting mutex is held
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*/
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struct rhashtable_params {
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size_t nelem_hint;
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size_t key_len;
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size_t key_offset;
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size_t head_offset;
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u32 hash_rnd;
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size_t max_shift;
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size_t min_shift;
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rht_hashfn_t hashfn;
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rht_obj_hashfn_t obj_hashfn;
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bool (*grow_decision)(const struct rhashtable *ht,
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size_t new_size);
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bool (*shrink_decision)(const struct rhashtable *ht,
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size_t new_size);
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int (*mutex_is_held)(void);
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};
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/**
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* struct rhashtable - Hash table handle
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* @tbl: Bucket table
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* @nelems: Number of elements in table
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* @shift: Current size (1 << shift)
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* @p: Configuration parameters
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*/
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struct rhashtable {
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struct bucket_table __rcu *tbl;
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size_t nelems;
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size_t shift;
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struct rhashtable_params p;
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};
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#ifdef CONFIG_PROVE_LOCKING
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int lockdep_rht_mutex_is_held(const struct rhashtable *ht);
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#else
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static inline int lockdep_rht_mutex_is_held(const struct rhashtable *ht)
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{
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return 1;
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}
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#endif /* CONFIG_PROVE_LOCKING */
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int rhashtable_init(struct rhashtable *ht, struct rhashtable_params *params);
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u32 rhashtable_hashfn(const struct rhashtable *ht, const void *key, u32 len);
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u32 rhashtable_obj_hashfn(const struct rhashtable *ht, void *ptr);
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void rhashtable_insert(struct rhashtable *ht, struct rhash_head *node, gfp_t);
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bool rhashtable_remove(struct rhashtable *ht, struct rhash_head *node, gfp_t);
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void rhashtable_remove_pprev(struct rhashtable *ht, struct rhash_head *obj,
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struct rhash_head __rcu **pprev, gfp_t flags);
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bool rht_grow_above_75(const struct rhashtable *ht, size_t new_size);
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bool rht_shrink_below_30(const struct rhashtable *ht, size_t new_size);
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int rhashtable_expand(struct rhashtable *ht, gfp_t flags);
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int rhashtable_shrink(struct rhashtable *ht, gfp_t flags);
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void *rhashtable_lookup(const struct rhashtable *ht, const void *key);
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void *rhashtable_lookup_compare(const struct rhashtable *ht, void *key,
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bool (*compare)(void *, void *), void *arg);
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void rhashtable_destroy(const struct rhashtable *ht);
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#define rht_dereference(p, ht) \
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rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht))
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#define rht_dereference_rcu(p, ht) \
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rcu_dereference_check(p, lockdep_rht_mutex_is_held(ht))
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#define rht_entry(ptr, type, member) container_of(ptr, type, member)
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#define rht_entry_safe(ptr, type, member) \
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({ \
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typeof(ptr) __ptr = (ptr); \
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__ptr ? rht_entry(__ptr, type, member) : NULL; \
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})
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#define rht_next_entry_safe(pos, ht, member) \
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({ \
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pos ? rht_entry_safe(rht_dereference((pos)->member.next, ht), \
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typeof(*(pos)), member) : NULL; \
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})
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/**
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* rht_for_each - iterate over hash chain
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* @pos: &struct rhash_head to use as a loop cursor.
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* @head: head of the hash chain (struct rhash_head *)
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* @ht: pointer to your struct rhashtable
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*/
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#define rht_for_each(pos, head, ht) \
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for (pos = rht_dereference(head, ht); \
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pos; \
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pos = rht_dereference((pos)->next, ht))
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/**
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* rht_for_each_entry - iterate over hash chain of given type
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* @pos: type * to use as a loop cursor.
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* @head: head of the hash chain (struct rhash_head *)
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* @ht: pointer to your struct rhashtable
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* @member: name of the rhash_head within the hashable struct.
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*/
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#define rht_for_each_entry(pos, head, ht, member) \
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for (pos = rht_entry_safe(rht_dereference(head, ht), \
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typeof(*(pos)), member); \
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pos; \
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pos = rht_next_entry_safe(pos, ht, member))
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/**
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* rht_for_each_entry_safe - safely iterate over hash chain of given type
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* @pos: type * to use as a loop cursor.
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* @n: type * to use for temporary next object storage
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* @head: head of the hash chain (struct rhash_head *)
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* @ht: pointer to your struct rhashtable
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* @member: name of the rhash_head within the hashable struct.
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*
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* This hash chain list-traversal primitive allows for the looped code to
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* remove the loop cursor from the list.
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*/
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#define rht_for_each_entry_safe(pos, n, head, ht, member) \
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for (pos = rht_entry_safe(rht_dereference(head, ht), \
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typeof(*(pos)), member), \
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n = rht_next_entry_safe(pos, ht, member); \
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pos; \
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pos = n, \
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n = rht_next_entry_safe(pos, ht, member))
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/**
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* rht_for_each_rcu - iterate over rcu hash chain
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* @pos: &struct rhash_head to use as a loop cursor.
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* @head: head of the hash chain (struct rhash_head *)
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* @ht: pointer to your struct rhashtable
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*
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* This hash chain list-traversal primitive may safely run concurrently with
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* the _rcu fkht mutation primitives such as rht_insert() as long as the
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* traversal is guarded by rcu_read_lock().
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*/
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#define rht_for_each_rcu(pos, head, ht) \
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for (pos = rht_dereference_rcu(head, ht); \
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pos; \
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pos = rht_dereference_rcu((pos)->next, ht))
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/**
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* rht_for_each_entry_rcu - iterate over rcu hash chain of given type
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* @pos: type * to use as a loop cursor.
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* @head: head of the hash chain (struct rhash_head *)
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* @member: name of the rhash_head within the hashable struct.
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*
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* This hash chain list-traversal primitive may safely run concurrently with
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* the _rcu fkht mutation primitives such as rht_insert() as long as the
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* traversal is guarded by rcu_read_lock().
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*/
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#define rht_for_each_entry_rcu(pos, head, member) \
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for (pos = rht_entry_safe(rcu_dereference_raw(head), \
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typeof(*(pos)), member); \
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pos; \
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pos = rht_entry_safe(rcu_dereference_raw((pos)->member.next), \
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typeof(*(pos)), member))
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#endif /* _LINUX_RHASHTABLE_H */
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